mysql建表-主键-索引-外键

create table employees (
id int(5) not null auto_increment ,
name varchar(8) not null,
primary key (id)
)
type＝innodb;

create table payroll(
id int(5) not null,
emp_id int(5) not null,
name varchar(8) not null,
payroll float(4,2) not null,
primary key(id),
index emp_id (emp_id),
foreign key (emp_id) references employees (id)
)
type = innodb;

表间一对多关系示例：